import logging
import traceback

import pymysql
from dbutils.pooled_db import PooledDB


class Pools:
    def __init__(self):
        self.POOL = PooledDB(
            creator=pymysql,  # 使用链接数据库的模块
            maxconnections=6,  # 连接池允许的最大连接数，0和None表示不限制连接数
            mincached=2,  # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
            maxcached=5,  # 链接池中最多闲置的链接，0和None不限制
            maxshared=3,  # 链接池中最多共享的链接数量，0和None表示全部共享。PS: 无用，因为pymysql和MySQLdb等模块的
            # threadsafety都为1，所有值无论设置为多少，maxcache永远为0，所以永远是所有链接都共享。
            blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
            maxusage=None,  # 一个链接最多被重复使用的次数，None表示无限制
            setsession=[],  # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
            ping=0,
            # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is
            # created, 4 = when a query is executed, 7 = always
            host='127.0.0.1',
            port=3306,
            user='root',
            password='6874',
            database='factory',
            charset='utf8'
        )

    def get_connection(self):
        return self.POOL.connection()

    def fetch_data(self, sql):
        conn, cursor = None, None
        result = ()
        try:
            conn = self.get_connection()
            cursor = conn.cursor()
            cursor.execute(sql)
            result = cursor.fetchall()
        except Exception as e:
            print(repr(e))
            logging.error(traceback.format_exc())
        finally:
            conn.close()
            cursor.close()
        return result

    def update_data(self, sql):
        conn, cursor = None, None
        try:
            conn = self.get_connection()
            cursor = conn.cursor()
            cursor.execute(sql)
            conn.commit()
        except Exception as e:
            print(repr(e))
            logging.error(traceback.format_exc())
        finally:
            conn.close()
            cursor.close()


db_pool = Pools()
